I have a 70 440 with 727 and 3.23 gears. have heard of a Aftermarket torque convertor that acts almost like a 4th gear at highway speeds but is not an overdrive or lockup unit. has anyone heard of this or used one?

Nope.

"I have heard" are the three most dangerous words.

A stock converter is probably closest to a lockup converter that you'd find in a 727 and nobody ever thought those had a fourth gear.

R.

That is what I have in there now, so you are saying I should keep what I have and it will help to reduce rpm's at highway speeds?

I am using a stock trans with only a shift kit for upgrades. I want to reduce engine rpm to put less strain on engine at highway speeds. 440 has 11.5 to 1 with 906 heads, 509 purple and hooker 3" out the back.

With 3.23 gears you shouldn't be running very high RPM. What size are your rear tires?

Then you need to add an overdrive of some sort, or change the rear end gearing. No big secrets here.

Pat

yes zzpat the secret is the convertor I am looking for!! had you read my original post I do not want to install an overdrive unit but have heard about a convertor that acts as a lockup or overdrive to reduce rpm and increase mileage.

BM used to make a convertor with a gearset in it but now I can't recall what they called it. Maybe John K does?
Tom

The B&M Superdrive Converter from the early eighties had an internal overdrive, it didn't stay around too long so I imagine it wasn't a great success.

http://papers.sae.org/820742/

"A torque converter has been developed for aftermarket use in older, heavier, large engined cars and light trucks to improve fuel economy, particularly at highway speeds. This torque converter includes an output coupled overdrive and torque split within the converter itself. This torque converter has shown gains in highway fuel economy of 9 to 21 percent. The converter changes that give the improved fuel economy result in a lower acceleration level for the vehicle"

John and StreetVanDan!
This is it, thank you. I googled for hours but found nothing as I was using the wrong name.
Tom

Tom, John and Streetvandan thanks that was what I had heard about just hoped they were still being made. was talking to a guy at a show last week who got one for his Buick GS. he just couldn't remember the name, maybe I will run into him again soon to find where he got his and will post the info for other members with b-bodies. Again I appreciate all your info.

The Buick guy may have been referencing the GM Switch-Pitch converter that was used in the late'60's which gives two different stall characteristics. I think they are available from an aftermarket source.